Silicone condensation reaction

ABSTRACT

A new silicone condensation reaction, the condensation between an alkoxy silane or siloxane and an organo-hydrosilane or siloxane and catalysts therefore is described and claimed.

The present invention relates to a new condensation reaction betweencompounds containing the hydrogen bonded directly to silicon(organo-hydrosilanes or organo-hydrosiloxanes) and alkoxy-silane orsiloxane which leads to the formation of siloxane bond and release ofhydrocarbons as a by-product.

BACKGROUND OF THE INVENTION

Two general processes can be applied for synthesis of organosiloxanepolymers; ring opening polymerization of cyclic siloxanes andpolycondensation. The polycondensation reaction between organofunctionalsilanes or oligosiloxanes leads to the formation of siloxane bond andelimination of a low molecular byproduct. The polycondensation of lowmolecular weight siloxanol oils is the most common method synthesis ofpolyorganosiloxanes and has been practiced for several years. Thebyproduct of this process is water. Unfortunately this method cannot beused for the synthesis of well-defined block organosiloxane copolymers.In that case the non-hydrolytic condensation processes can be employed.Many of such reactions are known and are frequently used:

-   1) the reaction of an organohalosilane with an organoalkoxysilane,    ≡Si—X+R—O—Si≡→≡Si—O—Si≡+RX;-   2) the reaction of organohalosilanes with organoacyloxysilanes,    ≡Si—X+RCOO—Si≡→≡Si—O—Si≡+RCOX;-   3) the reaction of organohalosilanes with organosilanols,    ≡Si—X+HO—Si≡→≡Si—O—Si≡+HX;-   4) the reaction of organohalosilanes with metal silanolates,    ≡Si—X+Metal-O—Si≡→≡Si—O—Si≡+MetalX;-   5) the reaction of organo-hydrosilanes with organosilanols,    ≡Si—H+HO—Si≡→≡Si—O—Si≡+H₂;-   6) the self-reaction of organoalkoxysilanes,    ≡Si—OR+RO—Si≡→≡Si—O—Si≡+ROR-   7) the reaction of organoalkoxysilanes with organoacyloxysilanes,    ≡Si—OR+R′COO—Si≡→≡Si—O—Si≡+R′COOR-   8) the reaction of organoalkoxysilanes with organosilanols,    ≡Si—OR+HO—Si≡→≡Si—O—Si≡+ROH-   9) the reaction of organoaminosilanes with organosilanols,    ≡Si—NR₂+HO—Si≡→≡Si—O—Si≡+NR₂H;-   10) the reaction of organoacyloxysilanes with metal silanolates,    ≡Si—OOR+Metal-O—Si≡→≡Si—O—Si≡+MetalOOR;-   11) the reaction of organoacyloxysilanes with organosilanols,    ≡Si—OOR+HO—Si≡→≡Si—O—Si≡+HOOR;-   12) the reaction of organooximesilane with organosilanols,    ≡Si—ON═OR₂+HO—Si≡→≡Si—O—Si≡+HN═OR₂;-   13) the reaction of organoenoxysilane with organosilanols,    ≡Si—O(C═CH₂)R+HO—Si≡→≡Si—O—Si≡+CH₃COR;

Those reactions can also be used for the formation of siloxane networksvia a crosslinking process. Many of the above processes require thepresence of catalyst such as protic acids, Lewis acids, organic andinorganic bases, metal salts and organometalic complexes. (See, forexample, (a) “The Siloxane Bond” Ed. Voronkov, M. G.; Mileshkevich, V.P.; Yuzhelevskii, Yu. A. Consultant Bureau, New York and London, 1978;and (b) Noll, W. “Chemistry and Technology of Silicones”, AcademiaPress, New York, 1968).

It is also well known in silicon chemistry that the organosilanol moietywill react with a hydrogen atom bonded directly to silicon(organo-hydrosilane) to produce a hydrogen molecule and thesilicon-oxygen bond, (See, “Silicon in Organic, Organometallic andPolymer Chemistry” Michael A. Brook, John Wiley & Sons, Inc., New York,Chichester, Weinheim, Brisbane, Singapore, Toronto, 2000). Although theuncatalyzed reaction will run at elevated temperatures, it is widelyknown that this reaction will run more readily in the presence of atransition metal catalyst especially noble metal catalysts such as thosecomprising platinum, palladium, etc., a basic catalyst such as an alkalimetal hydroxide, amine, etc., or a Lewis acid catalyst such as a tincompound, etc. Recently it has been reported that organo-boron compoundsare extremely efficient catalysts for the reaction between anorgano-hydrosilanes and organosilanols (WO 01/74938 A1). Unfortunately,the by-product of this process is dangerous, highly reactive hydrogen.

In spite of the foregoing developments, there is a continuing search fornew condensation reactions that will improve reaction's selectivity andsafety of the polycondensation process.

SUMMARY OF THE INVENTION

The present invention provides for a new condensation process to forminga silicon-oxygen bond comprising reacting an organosilane or siloxanecompounds bearing at least one hydrosilane functional group with anorganoalkoxysilane or siloxane compounds containing at least onealkoxysilane functional group and release of hydrocarbon as a byproduct,in the presence of a Lewis acid catalyst. The present invention alsoprovides for the formation of silicon-oxygen bond by reacting a compoundcomprising both at least one hydrosilane functionality and at least onean alkoxysilane moiety and releases hydrocarbon as a byproduct in thepresence of a Lewis acid catalyst.

Thus the present invention provides for a process for forming a siliconto oxygen bond comprising: (a) reacting a first silicon containingcompound said first silicon containing compound comprising a hydrogenatom directly bonded to a silicon atom with (b) a second siliconcontaining compound said second silicon containing compound comprisingan alkoxy group bonded to a silicon atom, in the presence of (c) a Lewisacid catalyst thereby forming a silicon to oxygen bond. The presentinvention also provides for a process for forming an silicon to oxygenbond comprising: (a) selecting a compound comprising both at least onehydrogen atom directly bonded to a silicon atom and at least one analkoxy group bonded to a silicon atom in said compound and (b) reactingthe hydrosilane functional group with the alkoxysilane group, in thepresence of (c) a Lewis acid catalyst thereby forming a silicon tooxygen bond. The processes of the present invention further provide formeans to produce compositions: siloxane foams, hyperbranched siliconepolymers, cross-linked siloxane networks and gels therefrom as well asother silicone and siloxane molecules exemplified herein.

DETAILED DESCRIPTION OF THE INVENTION

The present invention represents the discovery of a new type ofnon-hydrolytic condensation reaction for silicon bearing molecules.Generally, the reaction may be characterized as a condensation reactionbetween an organo hydrosilane or siloxane compounds bearing at least onehydrosilane moiety with an organoalkoxysilane or siloxane compoundscontaining at least one alkoxysilane moiety or functionality in thefollowing exemplary embodiment: the reaction of(M_(a)D_(b)T_(c)Q_(d))_(e)(R²)_(f)(R³)_(g)SiOCH₂R¹ and HSi(R⁴)_(h)(R⁵)_(i)(M_(a)D_(b)T_(c)Q_(d))_(j) yields a compound containing anew silicon-oxygen bond(M_(a)D_(b)T_(c)Q_(d))_(e)(R²)_(f)(R³)_(g)SiOSi(R⁴)_(h)(R⁵)_(i)(M_(a)D_(b)T_(c)Q_(d))_(j)and hydrocarbon (CH₃R¹) as the products. The subscripts a, b, c and dare independently zero or positive number; e, f, g, h, i, j are zero orpositive number subject to limitation that e+f+g=3; h+i+j=3; j=0, 1, 2;i=0, 1, or 2 subject to the limitation that i+j≦2. The other molecularcomponents have standard definitions as follows:M=R⁶R⁷R⁸SiO_(1/2);D=R⁹R¹⁰SiO_(2/2);T=R¹¹SiO_(3/2); andQ=SiO_(4/2)or drawn as structures (without any implied limitations ofstereochemistry):

The R¹ substituent is hydrogen or is independently selected from thegroup of one to sixty carbon atom monovalent hydrocarbon radicals thatmay or may not be substituted with halogens (halogen being F, Cl, Br andI), e.g. non limiting examples being fluoroalkyl substituted orchloroalkyl substituted, substituents R², R⁴, R⁶, R⁷, R⁸, R⁹, R¹⁰, andR¹¹ are independently selected from the group of one to sixty carbonatom monovalent hydrocarbon radicals that may or may not be substitutedwith halogens (halogen being F, Cl, Br and I), e.g. non limitingexamples being fluoroalkyl substituted or chloroalkyl substituted and R³and R⁵ are independently selected from the group consisting of hydrogen,one to sixty carbon atom monovalent alkoxy radicals, one to sixty carbonatom monovalent aryloxy radicals, one to sixty carbon atom monovalentalkaryloxy radicals and halogen.

Condensation of molecules that bear both functionalities, one(≡SiOCH₂R¹) and one (H—Si≡), on the same molecular backbone will lead toa formation of linear polymers unless the condensation reaction isconducted with a highly diluted substrate, in which case cycliccondensation products would be expected. Molecules that bear more thanone (≡SiOCH₂R¹) and only one (H—Si≡) functionalities on the samemolecular backbone as well as molecules that bear one (≡SiOCH₂R¹) andmore than one (H—Si≡) functionalities on the same molecular backbone areexamples of AB_(x) molecular structures. The condensation of theseAB_(x) compounds will lead to a formation of complex hyperbranchedcondensation polymers. The examples of such AB_(x) molecular structuresinclude but are not limited to:

Condensation of siloxane oligomers and polymers that bear more than one(≡SiOCH₂R¹) functional group with the siloxane oligomers and polymershaving more than one (H—Si≡) functionality is also possible and willlead to a formation of the cross-linked network. A preferred structureof the polymers with (≡SiOCH₂R¹) groups has the following formula:

where

G is OCH₂R¹; R¹, R², R⁴ has been defined before, m=0, 1, 2 . . . 5000;n=0, 1, 2 . . . 1000; o=1, 2, 3; p=0, 1, 2, 3; r=0, 1, 2 with limitationthat r+o=2 for internal siloxane and p+o=3 for terminal siloxane units.

A preferred structure of the polymer with (≡Si—H) groups has thefollowing formula:

where

R¹, R², R⁴ has been defined before, m=0, 1, 2 . . . 1000; n=0, 1, 2 . .. 100; t =0, 1, 2, 3 s=0, 1, 2, 3 with the limitation that t+s=2 forinternal siloxane units and t+s=3 for terminal siloxane units.

Other preferred compounds with (≡Si—H) groups are:

Cyclic Siloxanes:

where R² has been defined before and u=1, 2, 3, . . . 8; or branchedsiloxane:

where R² has been defined before and v=0, 1; w=3, 4

Condensation of siloxane oligomers and polymers that bear more than one(≡SiOCH₂R¹) moiety and more than one (H—Si≡) functionality is alsopossible and will lead to formation of a cross-linked network.

The above reaction is generally accomplished in the presence of anappropriate catalyst. The catalyst for this reaction is preferably aLewis acid catalyst. For the purposes herein, a “Lewis acid” is anysubstance that will take up an electron pair to form a covalent bond(i.e., “electron-pair acceptor”). This concept of acidity also includesthe “proton donor” concept of the Lowry-Bronsted definition of acids.Thus boron trifluoride (BF₃) is a typical Lewis acid, as it containsonly six electrons in its outermost electron orbital shell. BF₃ tends toaccept a free electron pair to complete its eight-electron orbital.Preferred Lewis acid catalysts include such catalysts as FeCl₃, AlCl₃,ZnCl₂, ZnBr₂, BF₃. The ability of any particular Lewis acid to catalyzethe new reaction of the present invention will be a function of acidstrength, steric hindrance of both the acid and the substrate andsolubility of the Lewis acid and the substrate in the reaction medium.Generally the following Lewis acids: FeCl₃, AlCl₃, ZnCl₂, ZnBr₂, and BF₃are only sparingly soluble in siloxane solvents and this low solubilitytends to interfere with the ability of these particular Lewis acidcatalysts to catalyze the desired reaction. Lewis acid catalysts havinga greater solubility in siloxane media are more preferred and preferablecatalysts include Lewis acid catalysts of formula (I)MR¹² _(x)X_(y)  (I)wherein M is B, Al, Ga, In or Tl; each R¹² is independently the same(identical) or different and represent a monovalent aromatic hydrocarbonradical having from 6 to 14 carbon atoms, such monovalent aromatichydrocarbon radicals preferably having at least one electron-withdrawingelement or group such as —CF₃, —NO₂ or —CN, or substituted with at leasttwo halogen atoms; X is a halogen atom; x is 1, 2, or 3; and y is 0, 1or 2; with the proviso that x+y=3, more preferably a Lewis acid ofFormula (II)BR¹³ _(x)X_(y)  (II)wherein each R¹³ are independently the same (identical) or different andrepresent a monovalent aromatic hydrocarbon radical having from 6 to 14carbon atoms, such monovalent aromatic hydrocarbon radicals preferablyhaving at least one electron-withdrawing element or group such as —CF₃,—NO₂ or —CN, or substituted with at least two halogen atoms; X is ahalogen atom; x is 1, 2, or 3; and y is 0, 1 or 2; with the proviso thatx+y=3, and is most preferably B(C₆F₅)₃.

The condensation reaction between the (≡Si—H) moiety and the (≡SiOR)moiety has some limitations, it appears that when three electronwithdrawing substituents are on the silicon containing (≡Si—H) bond suchas for example —OR, siloxane substituents or X (X=halogen) the reactionkinetics are slowed, sometimes to the point of inhibition of thereaction. Also the condensation reaction appears to require an alkoxysilane of the following structure (≡Si—O—CH₂—R¹) wherein R¹ is C₁₋₆₀alkyl, C₁₋₆₀ alkoxy, C₂₋₆₀ alkenyl, C₆₋₆₀ aryl, and C₆₋₆₀alkyl-substituted aryl, and C₆₋₆₀ arylalkyl where the alkyl groups maybe halogenated, for example, fluorinated to contain fluorocarbons suchas C₁₋₂₂ fluoroalkyl. The preferred alkoxy group is methoxy and ethoxygroup.

The process of the present invention utilizes a Lewis acid catalystconcentration that ranges from about 1 part per million by weight toabout 10 weight percent (based on the total weight of siloxanes beingreacted); preferably from about 10 part per million by weight (wppm) toabout 5 weight percent (50,000 wppm), more preferably from about 50 wppmto about 10,000 wppm and most preferably from about 50 wppm to about5,000 wppm.

The condensation reaction can be done without solvent or in the presenceof solvents. The presence of solvents may be beneficial due to anincreased ability to control viscosity, rate of the reaction andexothermicity of the process. The preferred solvents include aliphatichydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, as wellas oligomeric cyclic diorganosiloxanes.

The condensation reaction between the (≡Si—H) moiety and the (≡SiOCH₂R¹)moiety can be conducted at an ambient or at an elevated temperaturedepending on the chemical structures of reagents and catalysts,concentration of catalyst and used solvent.

In some cases it is desirable to blend siloxane oligomers or polymersthat bear at least one (≡SiOCH₂R¹) moiety with the siloxane oligomers orpolymers having at least one (H—Si≡) functional group and Lewis acidcatalyst. Subsequently the condensation reaction may be activated byheat. To extend the pot life of such a fully formulated mixture, theaddition of a stabilizing agent is recommended. The stabilizingadditives that are effective belong to the group of nucleophiles thatare able to form a complex with Lewis acids. These stabilizingadditives, preferably nucleophilic compounds, include but are notlimited to ammonia, primary amines, secondary amines, tertiary amines,organophosphines and phosphines.

The compositions produced according to the method or process of thisinvention are useful in the field of siloxane elastomers, siloxanecoatings, insulating materials and cosmetic products. The condensationreaction of (≡Si—H) terminated dimethylsiloxane oligomers withalkoxy-terminated diphenylsiloxane oligomers leads to a formation ofregular block siloxane copolymers with beneficial thermo-mechanicalproperties. The crosslinked material produced via condensation ofsiloxane oligomers and polymers that bear more than one (≡SiOCH₂R¹)moiety with the siloxane oligomers and polymers having more than one(H—Si≡) functional group will lead to a formation of novel siloxanecoatings and siloxane foams. A low cross-link density network frequentlyhas the ability to be swollen by lower molecular weight siloxanes orhydrocarbons thereby forming a gel. Such gels have found utility assilicone structurants for cosmetic compositions. Hyperbranched siloxanepolymers may be prepared by reacting the self-condensation of moleculethat bears more than one (≡SiOCH₂R¹) and one (H—Si≡) functionalities inthe presence of Lewis acid.

It is to be noted that silicon is a tetravalent element and for purposesof descriptive convenience herein, not all four bonds of the siliconatom have been described in some of the abbreviated chemical reactionscenarios used to explain the reaction chemistry involved in theformation of non-hydrolytic silicon oxygen bonds. Where silicon ishypovalent or hypervalent in terms of its customary stereochemistry, thefull structure has been indicated.

EXPERIMENTAL

-   1. Reaction of MD^(H) ₂₅D₂₅M with Me₂Si(OEt)₂.

A 50 ml flask was charged with 7.5 g of MD^(H) ₂₅D₂₅M (0.057 mol ofSi—H) and 3 g of Me₂Si(OEt)₂ (0.02 mol). The resulting low viscosityhomogenous fluid was heated to 100 g for 1 hr. No reaction was observed.This example demonstrates that the reaction requires appropriatecatalysis.

-   2. Reaction of MD^(H) ₂₅D₂₅M with MeSi(OEt)₃ in the presence of    B(C₆F₅)₃

A 50 ml flask was charged with 7.5 g of MD^(H) ₂₅D₂₅M (0.057 mol ofSi—H) and 3 g of MeSi(OEt)₃ (0.02 mol). The reagents were mixed to forma low viscosity homogenous fluid. 1000 ppm of B(C₆F₅)₃ as a 1.0 wt %solution in methylene chloride, was added to the flask. The resultingmixture was stable at room temperature for several hours. After heatingto 80° C. a very violent reaction occurred with rapid evolution of gas.The reaction mixture turned into foam in few seconds. This example showsthat addition of a suitable borane catalyst, B(C₆F₅)₃, promotes an rapidreaction between Si—H and SiOR. Conceivably this system could be used tomake a siloxane foam.

-   3. Self Condensation of (CH₃)₂Si(H)(OC₂H₅)

A 50 ml flask was charged with 10 g of dry toluene and 5.0×10⁻⁶ moles ofB(C₆F₅)₃ The resulting mixture was heated to 50° C. Next 5.2 g (0.05moles) of (CH₃)₂Si(H)(OEt) was added dropwise over a period of 30minutes. The exothermic reaction with gas evolution stared afteraddition of first few drops of alkoxy silane. The rate of addition wasadjusted to keep the reaction mixture temperature below 90° C. Afteraddition was completed, the resulting mixture was heated at 50° C. foran additional 60 minutes. The proton NMR showed 100% conversion of Si—Hand 90% conversion of Si—OEt. Si²⁹ NMR indicated the formation of linearalkoxy-stopped siloxane oligomers along with small amounts of D₃(hexamethylcyclotrisiloxane) and D₄ (octamethyl cyclotetrasiloxane).This low temperature process may also be carried out a room temperature.

-   4. Self Condensation of (CH₃)Si(H)(OCH₃)₂

A 50 ml flask was charged with 10 g of dry toluene and 5.0×10⁻⁶ moles ofB(C₆F₅)₃. The resulting mixture was heated to 50° C. Next 5.3 g (0.05moles) of (CH₃)Si(H)(OCH₃)₂ was added dropwise over a period of 30minutes. The exothermic reaction with gas evolution started after theaddition of the first few drops of alkoxy silane. The rate of additionwas adjusted to keep a mixture temperature below 90° C. After additionwas completed, the resulting mixture was heated at 50° C. for anadditional 60 minutes. The proton NMR showed 100% conversion of Si—H and50% conversion of Si—OCH₃. Si²⁹ NMR indicated formation of hyperbranchedsiloxane oligomers with Si—OCH₃ end groups.

-   5. Self Condensation of HSi(OC₂H₅)₃

A 50 ml flask was charged with 10 g of dry toluene and 5.0×10⁻⁶ moles ofB(C₆F₅)₃. The resulting mixture was heated to 50° C. Next 7.9 g (0.05moles) of HSi(OC₂H₅)₃ was added drop wise over a period of 30 minutes.The reaction temperature did not change, any gas evolution was observed.After addition of alkoxysilane was completed the resulting mixture washeated at 50° C. for an additional 60 minutes. The proton NMR showed 0%conversion of Si—H.

-   6. Condensation of (CH₃O)₂Si(C₆H₅)₂ with H—Si(CH₃)₂—O—Si(CH₃) ₂—H

A 50 ml flask was charge with 10 g of dry toluene and 5.0×10⁻⁶ moles ofB(C₆F₅)₃.

The resulting mixture was heated to 50° C. Next a mixture of 4.88 g(0.02 moles) of (CH₃O)₂Si(C₆H₅)₂ and 2.68 g (0.02 moles) ofH—Si(CH₃)₂—O—Si(CH₃)₂—H was added drop wise over a period of 30 minutes.The exothermic reaction with gas evolution stared after addition of thefirst few drops. After addition was completed the resulting mixture washeated at 50° C. for an additional 60 minutes. The proton NMR showed100% conversion of Si—H and 100% conversion of Si—OCH₃. Si²⁹ NMRindicated formation of cyclic compound (Si(C₆H₅)₂—OSi(CH₃)₂—O—Si(CH₃)₂—O)— and linear oligomers.

-   7. Condensation of (CH₃O)₂Si(C₆H₅)₂ with H—Si(CH₃)₂—Cl

A 50 ml flask was charged with 10 g of dry toluene, 2.93 g (0.03 moles)of HSi(CH₃)₂—Cl and 5.0×10⁻⁶ moles of B(C₆F₅)₃ and cooled down to 20° C.Next a mixture of 3 g (0.012 moles) of (CH₃O)₂Si(C₆H₅)₂ and 3.0 g oftoluene was added drop wise over a period of 30 minutes. The exothermicreaction with gas evolution stared after addition of the first drop.After addition was completed the resulting mixture was heated at 50° C.and low boiling components were stripped by application of a partialvacuum. The proton NMR showed 100% conversion of Si—H and formation ofchloro-stopped siloxane (ClSi(CH₃)₂—O—S(C₆H₅)₂—O—Si(CH₃)₂Cl). Si²⁹ NMRconfirmed formation of this compound.

-   8. Condensation of ((CH₃)₂CHO)₂SiC₂H₃ with H—Si(CH₃)₂—O—Si(CH₃)    _(2—H)

A 50 ml flask was charged with log of dry toluene and 5.0×10⁻⁶ moles ofB(C₆F₅)₃. The resulting mixture was heated to 50° C. Next a mixture of4.64 g (0.02 moles) of (iPrO)₃SiVi and 1.34 g (0.01 mol) ofH—Si(CH₃)₂—O—Si (CH₃)₂—H was added drop wise over a period of 5 minutes.The reaction temperature did not change, and no gas evolution wasobserved. After addition of regents was completed the resulting mixturewas heated at 50° C. for additional 60 min. The GC analysis did not showformation of siloxane oligomers. Example 8 shows that stericallyhindered alkoxysilanes such as isopropoxysilane or t-butyloxysilane donot react with Si—H in the presence of B(C₆F₅)₃. The condensationreaction requires the presence of —O—CH₂—R¹ alkoxide moiety attached tosilicon atom.

-   9. Reaction of MD^(H) ₂₅D₂₅M with MeSi(OMe)₃ in the presence of    B(C₆F₅)₃

A 10 ml flask was charged with 1.25 g of MD^(H) ₂₅D₂₅M (0.01 moles ofSi—H) and an appropriate amount of MeSi(OMe)₃. The reagents were mixedto form a low viscosity homogenous fluid. Next 160 ppm of B(C₆F₅)₃ wasadded. The cure kinetics of the above mixture was evaluated bydifferential scanning calorimetry (DSC: Perkin Elmer). The observed potlife, peak temperature and Delta H are presented in the following table:

Peak Delta Pot Exp. # Formula SiH/SiOR temp H J/g life/min 091-c884466-MeSi(OMe)3 0.63 53.4 561 >360 091-d 884466-MeSi(OMe)3 1.8 61.5174 45 091-e 884466-MeSi(OMe)3 1 57.4 310 >360

-   10. Reaction of MD^(H) ₂₅D₂₅M with OctylSi(OMe)₃ in the presence of    B(C₆F₅)₃

A 10 ml flask was charged with 1.25 g of MD^(H) ₂₅D₂₅M (0.01 moles ofSi—H) and appropriate amount of (C₈H₁₇)Si(OMe)₃. The reagents were mixedto form a low viscosity homogenous fluid. Next 160 ppm of B(C₆F₅)₃ wasadded. The cure kinetics of the above mixture was evaluated bydifferential scanning calorimetry (DSC: Perkin Elmer). The observed potlife, peak temperature and Delta H are presented in the following table:

Peak Delta Exp. # Formula SiH/SiOR temp H J/g Pot life/min 091-f884466-OctSi(OMe)3 1 47.5 745 20 091-g 884466-OctSi(OMe)3 0.66 62 196 20091-h 884466-OctSi(OMe)3 1.25 36.7 490 10

Examples 9 and 10 show that a mixture of Si—H siloxane with alkoxysilanein the presence of a catalytic amount of B(C₆F₅)₃ is stable at roomtemperature for a period ranging from 10 min to more than 6 hours. Theroom temperature stable mixture can be quickly reacted at slightlyelevated temperature. These experiments indicate that the mixtures fromexamples 9 and 10 could be used to produce thin siloxane coatings at alow temperature (below 80° C.). Such properties would be useful for lowtemperature paper release coatings and applications thereof.

The foregoing examples are merely illustrative of the invention, servingto illustrate only some of the features of the present invention. Theappended claims are intended to claim the invention as broadly as it hasbeen conceived and the examples herein presented are illustrative ofselected embodiments from a manifold of all possible embodiments.Accordingly it is Applicants' intention that the appended claims are notto be limited by the choice of examples utilized to illustrate featuresof the present invention. As used in the claims, the word “comprises”and its grammatical variants logically also subtend and include phrasesof varying and differing extent such as for example, but not limitedthereto, “consisting essentially of” and “consisting of.” Wherenecessary, ranges have been supplied, those ranges are inclusive of allsub-ranges there between. It is to be expected that variations in theseranges will suggest themselves to a practitioner having ordinary skillin the art and where not already dedicated to the public, thosevariations should where possible be construed to be covered by theappended claims. It is also anticipated that advances in science andtechnology will make equivalents and substitutions possible that are notnow contemplated by reason of the imprecision of language and thesevariations should also be construed where possible to be covered by theappended claims. All United States patents referenced herein areherewith and hereby specifically incorporated by reference.

1. A process for forming a silicon to oxygen bond in a compound comprising: a) selecting a compound comprising both a hydrogen atom directly bonded to a first silicon atom and an alkoxy group bonded to a second silicon atom in said compound and b) reacting the hydrosilane moiety with the silicon-alkoxy group, in the presence of c) a Lewis acid catalyst thereby forming a silicon to oxygen bond.
 2. The process of claim 1 wherein the Lewis acid catalyst comprises a compound of the formula: MR¹² _(x)X_(y) wherein M is selected from the group consisting of B, Al, Ga, In and Tl; each R¹² is independently selected from the group of monovalent aromatic hydrocarbon radicals having from 6 to 14 carbon atoms; X is a halogen atom selected from the group consisting of F, Cl, Br, and I; x is 1,2, or 3; and y is 0, 1 or 2; subject to the requirement that x+y=3.
 3. The process of claim 2 where M is boron.
 4. The process claims 3 wherein each R¹² is C₆F₅ and x=3.
 5. The process of claim 1 wherein the concentration of the Lewis acid catalyst ranges from about 10 wppm to about 50,000 wppm.
 6. The process of claim 1 wherein said process is stabilized by the addition of a compound selected from the group consisting of ammonia, primary amines, secondary amines, tertiary amines, organophosphines and phosphines.
 7. The process of claim 1 wherein said process is activated by heat.
 8. A process for the preparation of hyperbranched siloxane polymers utilizing the method of claim 1 wherein said compound comprises: a) more than one hydrogen atom directly bonded to more than one first silicon atom and only one alkoxy group bonded to one second silicon atom; or alternatively said compound comprises b) one hydrogen atom directly bonded to a first silicon atom and more than one alkoxy group bonded to more than one second silicon atom. 